WMV file with characteristics of probable tampering


New Member
Apr 26, 2017

1- ASF format video file (wmv file) made by a 4-channel dash cam recorder. Unknown maker, model and settings
2- frame rate: 4 FPS. That´s what happens when video is played
3- nominal frame rate: 30FPS
4- from frame 0 till 87 and from 172 on, 2 cams are updated at each frame, alternatively to the other 2 cams
5- from frame 88 till 171, a pair of even-numbered/odd-numbered (e.g 88/89, 90/91,...) shows the same image, changing all four cam images at a time
6- frame 149 is missing
7- there´s a 16-second jump in time showed by timestamps on frames 171 and 172

The mission is check authenticity of this file.

The main fact that catch anyone´s attention is item 7, that strongly suggests a cut off, but that is allegedly due to a recording system failure, according the person who provided the video.

It´s quite curious what happens in itens 5 and 6

In a small degree, item 3 doesn´t seem to comply to the average frames per second that are seen during playing.


New Member
Apr 26, 2017
Complimentary info:

8- Field "Creation Time" in "File Properties Object": 2016-2-11 10:23:12.686 (five days after accident). This field, according Advanced Systems Format (ASF) Specification, Revision 01.20.03, edited by Microsoft Corporation (December 2004), "specifies the date and time of the initial creation of the file. The value is given as the number of 100-nanosecond intervals since January 1, 1601, according to Coordinated Universal Time (Greenwich Mean Time).(...)"

It´s quite curious what happens in itens 5, 6 and 8.

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